[airbreather]

I work design/construction/commissioning engineering industrial machinery and plant, including automation/controls software.

On site standard days are 12 hours, crunch time 14's become normal. Depending on project this might be month on month off, 5 days on 2 days off, 8 + 6 days, sometimes every day 3 months straight, or more.

You do get used to it and can be overall productive for the hours - usually company is paying (big) by the hour so they wouldn't be paying if they are not getting.

Not everyone can do it, or wants to, but different people have different capabilities.

I've been doing it for decades.